Reposted from Dr. Roger Pielke Senior’s blog:
A New Perspective On Climate Science By L. Miller, F. Gans and A. Kleidon
It is not often that a new perspective is proposed in climate science, however, a set of two 2011 papers have done that (h/t to John Droz Jr!).
These papers are
Miller, L. M., Gans, F., and Kleidon, A.: Estimating maximum global land surface wind power extractability and associated climatic consequences, Earth Syst. Dynam., 2, 1-12, doi:10.5194/esd-2-1-2011
with the abstract
“The availability of wind power for renewable energy extraction is ultimately limited by how much kinetic energy is generated by natural processes within the Earth system and by fundamental limits of how much of the wind power can be extracted. Here we use these considerations to provide a maximum estimate of wind power availability over land. We use several different methods. First, we outline the processes associated with wind power generation and extraction with a simple power transfer hierarchy based on the assumption that available wind power will not geographically vary with increased extraction for an estimate of 68 TW. Second, we set up a simple momentum balance model to estimate maximum extractability which we then apply to reanalysis climate data, yielding an estimate of 21 TW. Third, we perform general circulation model simulations in which we extract different amounts of momentum from the atmospheric boundary layer to obtain a maximum estimate of how much power can be extracted, yielding 18–34 TW. These three methods consistently yield maximum estimates in the range of 18–68 TW and are notably less than recent estimates that claim abundant wind power availability. Furthermore, we show with the general circulation model simulations that some climatic effects at maximum wind power extraction are similar in magnitude to those associated with a doubling of atmospheric CO2. We conclude that in order to understand fundamental limits to renewable energy resources, as well as the impacts of their utilization, it is imperative to use a “top-down” thermodynamic Earth system perspective, rather than the more common “bottom-up” engineering approach.”
and
Kleidon, Axel, 2011: How does the earth system generate and maintain thermodynamic disequilibrium and what does it imply for the future of the planet? Article submitted to Royal Society. arXiv:1103.2014v1 [nlin.AO] 10 Mar 2011
with the abstract
“More than forty years ago, James Lovelock noted that the chemical composition of the earths atmosphere far from chemical equilibrium is unique in our solar system and attributed this to the presence of widespread life on the planet. Here I show how this rather fundamental perspective on what represents a habitable environment can be quantified using non-equilibrium thermodynamics. Generating disequilibrium in a thermodynamic variable requires the extraction of power from another thermodynamic gradient, and the second law of thermodynamics imposes fundamental limits on how much power can be extracted. When applied to complex earth system processes, where several irreversible processes compete to deplete the same gradients, it is easily shown that the maximum thermodynamic efficiency is much less than the classic Carnot limit, so that the ability of the earth system to generate power and disequilibrium is limited. This approach is used to quantify how much free energy is generated by various earth system processes to generate chemical disequilibrium. It is shown that surface life generates orders of magnitude more chemical free energy than any abiotic surface process, therefore being the primary driving force for shaping the geochemical environment at the planetary scale. To apply this perspective to the possible future of the planet, we first note that the free energy consumption by human activity is a considerable term in the free energy budget of the planet, and that global changes are closely related to this consumption of free energy. Since human activity and associated demands for free energy is anticipated to increase substantially in the future, the central question in the context of future global change is then how human free energy demands can increase sustainably without negatively impacting the ability of the earth system to generate free energy. I illustrate the implications of this thermodynamic perspective by discussing the forms of renewable energy and planetary engineering that would enhance overall free energy generation and thereby ”empower” the future of the planet.”
In response to the first paper, I contacted Axel Kleidon with the following e-mail on April 4 2011
Hi Axel
I have one question so far. The winds are created by spatial gradients in heating and cooling. The westerlies, for example, result since it is colder through the troposphere at higher latitudes than equatorward. Sea breezes occur due to a warmer lower troposphere over land adjacent to cooler, stably stratified ocean water.
While I can see how vast areas of wind turbines could alter the pattern of heating and cooling (and thus alter the wind patterns to an extent) – both due to their waste heat and alteration of surface fluxes of heat, moisture and momentum, I do not see how the kinetic energy is lost as it is just redistributed. The waste heat, for example, still would be spatially heterogeneous and would generate wind flow.
One would need to show that the gradients of warm and cool regions are reduced as a result of the wind turbines to show a global average reduction in “free energy”.
Let me know how this issue is handled. Meanwhile, I will keep studying your paper! 🙂
Best Regards
Roger
He responded with the reply on April 11 2011
Thanks for your question.
One critical aspect is that the strength of the atmospheric circulation is thermodynamically limited and that it already operates near maximum strength (i.e. maximum power, or equivalently, maximum generation of kinetic energy, or maximum dissipation or maximum entropy production — they all yield about the same). This can be shown relatively easily by quantifying how much power can be drawn out of the hemispheric gradient in solar irradiation. The derivation essentially follows the Carnot limit, except that the Carnot limit makes two critical assumptions that do not apply for the atmosphere:
* First, the Carnot limit assumes that there are no other irreversible processes within the system that compete for the same gradient. In the atmosphere, emission of radiation depletes the same hemispheric insolation gradient, so that kinetic energy generation competes with emission of terrestrial radiation. This reduces the maximum efficiency by a factor of 2.
* Second, the generation of kinetic energy and the associated heat transport depletes the temperature gradient that drives the generation. This reduces the maximum efficiency by another factor of 2.
The resulting maximum thermodynamic efficiency is about 2%, or 900 TW, which is very close to what is estimated from observations. In other words, the large-scale atmospheric circulation is approx. as strong as possible. In essence, this is the same as the maximum power principle in electrical engineering. This derivation is shown in section 4.3 and 4.4 of the attached.
When kinetic energy is extracted from the boundary layer, then it is obviously limited to what is generated within the atmosphere. Actually, it is a lot less, again because of thermodynamic limits (you cannot bring the atmosphere to a standstill). Furthermore, much of the areas are not accessible: 1/2 of the KE is dissipated in the free atmosphere, and of the remaining, 3/4 are dissipated over oceans. That alone leaves only 112.5 TW, of which, as said before, not all can be extracted. The GCM simulations that we did support the line of reasoning as well as the orders of magnitude.
The waste, dissipative heat plays practically no role since it is very small compared to the forcing in solar irradiation.
Hope these explanations help, otherwise I’d be happy to explain more.
I asked a follow up question on April 14, 2011
Hi Axel
I plan to post sometime next week. However, I have another question. As you are aware, terrain extracts kinetic energy from the atmosphere even in the absence of any surface frictional effects (e.g. see pages 459 to 462 in the 2002 version of my modeling book).
What would be an equivalent terrain feature and impinging wind and stability that would result in the same limit from the wind extraction due to wind turbines? This would help in scaling the issue and providing another perspective.
Best Regards
Roger
Axel promptly replied
Hi Roger,
I think the best case (but still vague) are waves and sand dunes.
Waves generate roughness and should thereby extract more momentum from the atmosphere. The power involved in wave generation is about 63 TW (from the MIT people, Ferrari and Wunsch I think) and this power is taken from the kinetic energy of the atmospheric boundary layer. Now, we could ask if this is maximized. A rough estimate would be like this: 450 TW of dissipation within the boundary layer, 3/4 of which over the ocean, and if we take 1/3 of being extractable, we get about 110 TW, which is not too far off. And, after all, waves are not as high as wind turbines, so we should expect a lot less.
Another example would be the effect of dunes in sand transport, for which it has been proposed that dune formation maximizes sand transport. From an atmospheric point of view, this would mean maximum extraction of kinetic energy to drive the sand transport.
An issue with models (as far as I know how models handle this issue), by the way, is that they dissipate this transferred free energy by turbulence rather than transferring it to the ocean or to the sand. Oceans are usually driven by wind drag, but the resulting power input has already been dissipated by the model’s drag parameterization in the atmospheric boundary layer. So this should be quite an inconsistency in the coupling of models, with effects on the turbulent fluxes. I really think this points out that models do not handle interactions correctly at system boundaries with respect to free energy transfer.
Hope these thoughts help clarify some of the issues.
Best,
Axel
My follow up on April 14 2011 was
Hi Axel
Thank you for the quick feedback.
There is still the issue of “form drag” that I wrote on in my e-mail. This is related to pressure forces, not the friction. Even small obstacles have this. For a 2-D hill (or mountain), as I show on page 462 of my book, it is given by
wave drag = the integral in x of the pressure as a function of x along the terrain slope times the x-gradient of the terrain.
This will occur in inviscid flow, but also in turbulent flow. Wind turbines would have this effect in addition to turbulent dissipation of the wind.
Large scale models do have parameterizations for this wave drag effect from terrain but not from other surface features that I am aware of. They use a aerodynamic roughness based formulation (i.e. frictional drag), but this is not the way it should be done with respect to form drag. In terms of your GCM runs with wind turbines, I assume you handled this just with frictional drag (page 4 of your paper). I assume one could interpret form drag as be part of C(sub ext),of course, but it might be useful to break into the two forms of drag.
I agree with you on the way models mishandle sand transport (and sea water spray also) as we discuss in our paper
Pielke, R.A. and T.J. Lee, 1991: Influence of sea spray and rainfall on the surface wind profile during conditions of strong winds. Bound.-Layer Meteor., 55, 305-308.
http://pielkeclimatesci.files.wordpress.com/2009/09/r-125.pdf
We wrote in our abstract that
“Janin and Cermak (1988) have: determined that airborne sediment in a wind tunnel substantially alters the low-level wind profile. This material apparently causes a reduction in wind speed since the pressure gradient force must accelerate both the air and the sediment, against the force of surface shearing stress.”
and then applied this concept to sea spray, where we wrote
“In this brief paper, we explore whether atmospheric wind profiles would be expected to be modified during periods of high winds as a result of heavy rainfall or sea spray. Although there has been controversy regarding the effect of sediment load on pressure drop (e.g., Rangaraju, 1988), our assumption that the wind profile rem~ins logarithmic is based on the physical modeling of Janin and Cermak (1988) in which even with sand loading in the atmosphere, the square root of the total kinetic energy profile remains logarithmic. This means that a given pressure gradient force can accelerate either air, or a combination of air and a suspended material but when suspended material is present, the actual air velocity will be less.”
I am really intrigued by your ideas, and appreciate the opportunity to discuss with you.
Best Regards
Axel replied on April 27 2011
Hi Roger,
[S]orry for the delay, I was on vacation and my internet connection collapsed when my iPad asked for a factory restore that required an internet connection…
Yes, I agree regarding your comment about form drag, which we did not consider. We originally added extra roughness to the frictional drag, but then separated this into the extra term C_ext. In principle, one should be able to add a separate form drag to this, although this would likely depend on the turbine characteristics and the wind park layout and makes this more complicated. I guess the effect of considering the form drag would lead to an even lower efficiency of what can be extracted from the wind and converted into useful power. Any extra “complication” seems to degrade thermodynamic efficiencies…
Thanks very much for sending the link to your paper! Yes, it is basically what I am talking about regarding the misrepresentation, with the addition that a maximum of power transfer from air flow to sand flow could help to quantify/constrain the interaction between air and sand flow.
Likewise, I enjoy this discussion with you very much as well.
Best,
Axel
I look forward to hearing more on Axel’s research on this topic!
One hundred years ago America tossed windmills and electric cars on the junk heap for a reason, they were not efficient.
Considering that wind turbine affect up to a height of 200m at best and that the thickness of polar anticyclones is 1500m one really wonders how the GCM used are truly reflecting the reality of atmospheric circulation. Once again Leroux observations become critical to modelling. “Dynamic Analysis of Weather and Climate”, Springer/Praxis 2010
There will come a time when Adam Smith’s invisible hand will tell us that wind turbines make economic sense. In the meantime energy can still be had just for the cost of pumping it out of the ground.
Clearly he is misinformed. All Apple products are perfect, and are NOT made by Chinese children under horrendous working conditions.
The potential for wind power considering all land based wind is between 18-34 TW. A turbine uses something like 20 acres of land to avoid turbulent wind effects from neighboring wind turbines. People who make estimates of total power available fail to look at the land use. While many locations that are good potential sites for a wind farm, the potential destruction of aesthetic natural views is worry some because the areas are remote and have great natural beauty. Despite the availability of wind, some of the areas are places of great natural beauty and many would view a wind farm as hostile to the view of the landscape. It is also clear that wind farms is populated areas are becoming leas and less accepted including the expansion of existing farms. The question is how much land area is really available for use as a wind farms. Personally, I would be really upset if New Mexico ended up looking like Palm Springs California. As I look out my window I can see the High Lonesome Mesa wind farm and it isn’t hard to imagine that the whole 30 miles of mesas could end up with hundreds of wind turbines with their ugly blinking red lights.
The thing is not that wind is inefficient, but that it is being oversold with the amount we can use overstated and the difficulty of using way underestimated. There are still places and tasks for which windmills are the best answer. Sailing ships still work as well as they ever did and there are areas where they are still the best. Likewise there are applications where electric vehicles are optimum. It’s just pretending these things are the grand glorious answer to everything that’s silly.
Nice try, but don’t get too carried away. It’s a model. We are constantly griping about people making too much out of models. Eh.
Uh, didn’t you forget one thing? The third dimension? If you build UP, you can do more than planting a forest of windmills on the ground – and then you might have some significant effects.
Otherwise, I would not be surprised if windmills are not much more than another kind of tree. What are the turbulent effects of trees? What is the effect of transpiration on the local atmosphere? Is evaprative cooling much different than taking energy away through a wind turbine? There must be a net removal of energy, and that could translate into cooling as well as reduced wind speed.
Also, there are other external limiting factors such as windmill self-destruction that impose a spacing requirement of about 1/3 to 1/2 of a mile (to avoid fratricide). That works out to about 80 acres for each windmill. Sure enough, if you look at the actual number of acres per windmill on windfarms, you get an average of 80 acres per turbine. My calcs show that it would take about 10,000 1.5 MW generators (considering the capacity factor) to produce 10% of California’s energy needs, and these would require 1250 square miles of land. There’s some opportunity cost! But given the limited acres with class 5 windspeed, you have to install them off shore.
The paper is a nice exercise, but it isn’t much more than that. Don’t take it too seriously. Models. I think they are cool, but they are toys in the end. Hey, here’s an idea: Try the same thing for PV or other solar. You know, the solar updraft tower concept might be very intersting to analyze.
What would be interested would be to the see figures put into context. How does wind energy compary with other existing and potential sources (coal, oil, waves, sun etc.)
I can’t imagine we’d ever put up enough windmills to bring us anywhere near close to the theoretical limits they propose. But if we did, we’d be messing up the length of day calculations?
It is very encouraging to read someone who understands that, as I have been saying for some years, the climate is always “running as fast as it can”. This makes the modeling of such a system much different than the mechanistic model paradigm used in the GCMs.
w.
It is good (I suppose) that scientists are doing this kind of research to better understand how wind ‘works’.
But, as far as using wind as a primary energy resource is concerned, you don’t even need to know the basic laws of thermodynamics. The results are in and (in most cases) are there to be seen.
It costs a fortune and cannot be relied upon to provide power when it is needed.
We knew that ten years ago.
As @genomega1 says: May 5, 2011 at 8:57 pm
we knew that 100 year ago.
A bigger and more efficient and better designed version of something that doesn’t work is still very likely not to work.
My antecedents in Yorkshire were a hard-headed lot, being born into that demanding environment tends to inculcate a sense of realism in any world view. Getting ‘owt for nowt’ was crossed off the Yorkies’ wish-list aeons ago. Still seems realistic to me.
I recall that Axel Kleidon’s work was mentioned in an April 2011 copy of New Scientist. I was surprised enough that I actually bought a copy of “Nude Socialist”. My first in years. I understand that true believers may have got their noses out of joint and that there was some hand waving and qualification (muddying the waters) for the web edition.
I feel Axel Kleidon’s work is reasonably accurate, in that wind turbines cannot replace hydrocarbon fuels. I would even venture that the prediction of climatic effects of too many wind turbines has a greater foundation in provable atmospheric physics than does the CO2 AGW hypothesis. However it should be noted that while wind turbines cannot achieve their stated objectives, they can serve their intended objectives, namely, subsidy farming, green washing and creating an artificial energy crisis.
I could see that a similar study on photovoltaic solar panels may also have some merit. Typical panels convert less than 15% of visible light at 90 degrees incidence to electricity. How much incoming radiation do they reflect? How much do they absorb and re-emit as heat? What would really happen to earths temperature if we replaced all our hydrocarbon fuels with current photovoltaic technology?
Rather than say the climate is ” running as fast as it can ” it would be more proper to say that the world is trying its hardest to reach equilibrium, chasing its tail with all the constant lopsided imputs, thus we have weather, sometimes good and oft times not so good.
As near I can make out, they are considering only land-based wind power in this study. Seems an odd limitation?
@Martin Brumby:
I’m not sure how the “wind is expensive” mantra survives. WattsUpWithThat published an image a few days ago showing the new-build cost of various energy sources – it shows wind is equal with coal (give or take 2%) and substantially cheaper than nuclear (by about 15%). And, yes, that’s coal with out carbon capture.
@Hoser:
I’m afraid that’s rather magical thinking. Windmills extract energy; the energy must come from somewhere. Trees don’t extract energy (at least not from the wind), though they do act as a drag.
If you look into wind turbines and trees, you will find that turbines have quite finely designed aerodynamic blades, while trees do not. There are also not many trees 450 feet tall!
There is a joke I have heard of two Norwegians in Minnesota who have a 10 ton truck and are buying hay for $40/ton only to sell it for $35 a ton in a neighbouring town. So one says to the other “We need to buy a bigger truck.”
I am afraid I think of this whenever I hear of wind power.
(I am married to a Norwegian who is many times cleverer than I, as are her two sisters, but some of the mid-west Norwegian jokes are quite funny.)
Willis Eschenbach says:
May 6, 2011 at 12:23 am
“It is very encouraging to read someone who understands that, as I have been saying for some years, the climate is always “running as fast as it can”. This makes the modeling of such a system much different than the mechanistic model paradigm used in the GCMs.”
This is a very important point for many reasons. This idea needs to be put on paper in a way that it grabs the attention of everyone. In the realm of ideas, what is needed is a really good visualization of the climate running as fast as it can. It should replace the often trumpeted image of serene Gaia who suffers for our sins.
[snip . . try Tips & Notes]
Tom says:
May 6, 2011 at 4:24 am
“I’m not sure how the “wind is expensive” mantra survives. WattsUpWithThat published an image a few days ago showing the new-build cost of various energy sources – it shows wind is equal with coal (give or take 2%) and substantially cheaper than nuclear (by about 15%). And, yes, that’s coal with out carbon capture.”
a) The mantra survives because wind power still get subsidized. Must have a reason, don’t you think so?
b) New build wind power as cheap as coal power? Where do you have that from? From here?
http://www.iea.org/Textbase/npsum/ElecCost2010SUM.pdf
Notice that they assume a prize of 30 USD per tonne of CO2 emissions; so i guess that helps wind a bit.
@Tom says: May 6, 2011 at 4:24 am
[ ] @Martin Brumby:
“I’m not sure how the “wind is expensive” mantra survives.”
Because this “mantra”, as you put it, is the unvarnished truth.
I’m not sure how BigWind survives.
It is absolutely certain that without massive subsidies on the one hand and forcing electricity distribution companies to buy it at uncommercial rates and also making them invest in new distribution networks and charge the consumers, no one would even think of using wind for power generation.
Far too expensive.
Far too unreliable.
Wind power is just a scam and I know it. I have to pay for it in my energy bill.
@Martin Brumby:
“I’m not sure how the “wind is expensive” mantra survives. WattsUpWithThat published an image a few days ago showing the new-build cost of various energy sources – it shows wind is equal with coal (give or take 2%) and substantially cheaper than nuclear (by about 15%). And, yes, that’s coal with out carbon capture.”
Problem is that’s wind under optimum conditions (and probably with maintenance costs underestimated). Wind is fine — Really it is — if you have only a few turbines feeding the grid. Or if you are trying to pump water into a tank to use to supply a trough for watering stock someplace out in the mountains of the Great Basin miles from the nearest anything. The problem is that the cost of wind is always figured assuming that the grid can handle every watt the turbines generate. The grid can not do that when there are a lot of turbines feeding it. Not today. Maybe not ever.
One possible answer might be a wind farm combined with some flexible form of generation – hydro or natural gas. Have the whole thing owned and operated by one entity and contracted to deliver specified amounts of power with a specified availability profile. If the costs of that are competitive, then why would anyone complain? (But there is no reason whatsoever to subsidize that except possibly the R&D and proof of concept).
As the Ill-Tempered Klavier says. Where wind is an optimal technology, there’s no reason not to use it.
Coal power is about $485 per installed kW (2010)
Nuclear (French, light water fast breeder U238) is about $5500-8100 per kW (2008)
Nuclear (Canadian, heavy water, U235) $1000 per kW (2003)
Nuclear (Thorium-flouride) is probably $500 per kW but nothing on offer
Nuclear (South Africa, PBMR) not admitted, relatively cheap, presently shelved
Wind is $1,200-2400 per kW (2011)
Given the lunacy attached in the anti-nuclear power industry, no wonder people burn coal, a direct response to Euro-Greenie mental madness and violence (ignored in France).
Glad to be Canadian.
And if the wind is blowing at the wrong time
http://www.telegraph.co.uk/earth/energy/windpower/8486449/Wind-farms-paid-900000-to-switch-off-for-one-night.html
“Wind farms operators were paid £900,000 by the National Grid to disconnect their turbines for one night because the electricity was not needed. “
These principles suggest that the severity of yearly hurricanes could be sharply reduced by using enough wave energy out at sea. That would be wonderful. No more Katrinas, just lesser hurricanes.
But then there is the Law of Unintended Consequences. No argument, the climate will be altered. But how?
And don’t forget that wind power is only nuclear power by proxy. So id Greenies like nuclear power so much, why will they not let us use it here?
.
When you discover the Energy Returned On Energy Invested EROEI for wind power everything else having to do with this “alternative” energy comes into focus.
By my calculations the EROEI for Livermore Pass, the only analysis I have been able to find, is not 14.87 as claimed but 0.29.
This is why proponents huckstering wind power talk in subjectives and avoid engineering analysis. Wind power is unsustainable – period.
I may be mis-interpreting the point here, but a cursory read indicates an assumption in their calculations that appears to violate the laws of thermodynamics, big enough to drive a truck (without emission controls) through – therefore, my overall take on their message is that it is superfluous and distracting noise.
On the overall subject of energy harvested from existing natural flow patterns all around us – the economics and feasibility will doubtless look a lot better when actually useful solutions to borrow this energy all around us is realized. One of my primary digs against current wind (and hydro) schemes is that they’re doing it wrong. Bird killing, inefficient, butt ugly giant pinwheels are not the answer. Massive obstructions to water courses that trap water (often times at ‘uh oh, there’s not as much as we thought’ rates, driving self-induced crisis)(or alternately leading to ‘uh-oh, that’s a heck of a lot more than we thought it would be’ rates, temporarily, also driving self-induced crisis) – those are just as inefficient and wrong.
As for a reason? Well, seems there’s a lot more money to be made, and a lot more self licking ice cream cone style activity created in the myopic view that realizes working on failure under the delusion of ‘winning’ (no, I have no idea what Charlie means when HE says it) than just creating something that works.
two things:
1. the guys that design these windmills need to review the blueprints for the golfball (spherical monosupport) water towers. towers built in the late thirties withstand tornados, earthquakes …… quite well. maybe those “good ol boys” might have something there. for those doubters simply calculate the weight of a 100′ steel sphere made of 1″ plate full of water and think about it for awhile.
2. what effect does the white or light grey color that the current offerings are painted have on the local wind patterns. there seems to be literally acres of white paint on those things and it would seem that that would heat the air in the local area several degrees above normal thereby giving wind less effect due to lower barometric pressure around the site.
hey this is the world where a quater of a froghair is the difference between sucess and failure.
C